Range-finder.



J. s. BOYUM. RANGE FINDER.

APPLIOATION PILED OUT. 28, 1910- RENEWED MAY 23. 1912.

. 1,032,874.. Patented July 16, 1912.

'7 SHEETSSHEET 1.

J. S. BOYUM.

RANGE FINDER.

. APPLICATION IILED OUT. 28, 1910. RENEWED MAY 23. 1912. 1,032,874. Patented July 16, 1912.

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J. S. BOYUM.

- RANGE FINDER. APPLICATION FILED 001:. 2a, 1910. RENEWED MAY 23, 1912.

1,032,874. Patented July 16, 1912.

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COLUMBIA PLANOORAPEX CO..WASH\NGTON. D. c.

Wilfizems WM WW J. S. BOYUM.

RANGE FINDER.

APPLICATION FILED OUT. 28, 1910.. RENEWED MAY 23, 1912.

1,32,874. Patented July 16, 1912.

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RANGE FINDER. APPLIOATION FILED 001?. 28, 1910. RENEWED MAY 23, 1912.

Patented July 16, 1912.

7 SHEETS-SHEET 5.

J. S. BOYUM.

RANGE FINDER. APPLICATION FILED OOT ZB, 1910. RENEWED MAY 23, 19.12.

1,032,874.. I Patented July 16, 1912.

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COLUMBIA PLANOURA TON. D. c.

J. BOYUM.

RANGE FINDER.

APPLICATION FILED new. 28, 1910. RENEWED MAY 23, 1912.

1,032,874. PatentedJuly 16, 1912.

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UldiTED STA FES PATENT QFFICE.

JOHN S. BOYUM, OF NASHVILLE, TENNESSEE.

RANGE-FINDER.

Application filed October 28, 1910, Serial No. 589,509.

To all whom it may concern:

Be it known that I, JOHN S. BOYUM, a citizen of the United States, residing at Nashville, in the county of Davidson and State of Tennessee, have invented new and useful Improvements in Range-llinders, of which the. following is a specification.

My present invention relates to improvements in range finders whereby distances between given point and different objects may be determined, and the invention consists in certain improvements in aninstru ment of this character whereby the errors occurring in the ultimate results of finding ranges are reduced to a minimum.

In the accompanying drawing, I have shown the range finder constructed in ac cordance with my invention. It is to be understood that the invention is not. necessarily limited to the exact construction shown in the drawing, as the drawing illustrates but one embodiment of the invention and constructions equivalent to those shown in the drawing will be included within the terms of the claims annexed to the specifiation.

In the accompanying drawings :Figure 1 represents a top plan view of a range finder constructed in accordance with one embodiment of the invention, the same being viewed from the exterior; Fig. 2 is a detail perspective view of a portion of the casting which serves to firmly support and rigidly maintain the optical parts and the rangefinding mechanism in proper relation; Figs. 3 and 4; are sectionai views of one end of the range finder showing in top plan view and elevation respectively the mounting for one of the primary reflectors; Fig. 5 is a top plan view of the range-finding mechanism, the inclosing casing being shown in section; Fig. (5 is an elevation of the. range-finding mechanism as viewed from the bottom in Fig. 5, the inclosing casing in this view being also broken away; Fig. 7 represents a vertical section through the range-finding mechanism, and also its inclosing casing; Fig. 8 is a detail sectional view taken axially of the range-finding eye-piece and the screw and carriages constituting part of the range-finding mechanism, the eye-piece being focused for rangefinding, and the shield for separating the parts of the image during standardization of the instrument with a target being shown in inoperative position; Fig. 9 is a detail perspective Vie? Of the car- Specification of Letters Patent.

Patented July 1.6, 1912. Renewed May 23, 1912. Serial No. 699,280.

riage and the secondary reflectors which are attached. to such carriage; Fig. 10 is a detail. perspective view of the carriage which cooperates with the range-finding screw and detachably receives the carriagesupporting the secondary reflectors, this view also showing the takeup device for preventing backlash between the range-finding screw and its carriage; Fig. 11 is a detail perspective view of the shield detached from the eye-piece support, this shield serving when the eye piece support is focused for the target to divide or separate the two parts of the image; Fig. 12 is a detail perspective view of the adjustable section of the eye-piece carrier, this view also showing the front and rear stops for positioning the eyepiece both for target and range-finding adjustments; Fig. 13 is a detail view of the rear eye-piece support; Fig. 14 represents an axial section of the shaft for standardizing the instrument at infinity adjustment and also the device for regulating the back-lash between the infinity and range-finding adjustments; Fig. 15 represents a top plan View of the parts shown in Fig. 14 with the adjusting head detached; Fig. 16 represents a transverse section of the back-lash regulating device on the line 1616 of Fig. 14; Fig. 17 shows in perspective the parts composing the latch for detachably locking the hand-wheel or head to the cooperative parts in Fig. 14; Fig. 18 shows in perspective. parts of the back-lash regulating device as shown in Fig. 16; Fig. 19 is a. perspective View of part of the back-lash regulating device as viewed from the under side; Fig. 20 is a perspec tive view ot-those parts of the machanism composing the brake for automatically arresting the movement of the traveling tape when it approaches the infinity mark in one direction andv the end of the tape in the opposite direction, and also the interlock whereloy operation of the infinity adjustn'ient is prevented except. when the instrument is set for the infinity adjustment, and during the infinity adjustment, the tape is locked from movement; Fig. 21 is a view similar to Fig. 20 except that the brake in this figure is shown set to arrest the movement of the tape, the infinity adjustment is set for operation, and this infinitv adjustment locks the tape from movement; Fig. 22 is a detail sectional view of'the brake showing it in cooperative relation with the brake flange on the tape-operating gear; and Fig. 23 isa detail sectional view of the clip for .detachably locking the infinity adjustment shaft in operative position.

Similar parts are designated by the same reference characters in the several views.

In that embodiment of the invention shown in the accompanying drawing, the optical parts and the cooperative rangelinding mechanism are firmly supported and rigidly maintained in proper operative re lation by means of a support 1 which is preferably composed of a one-piece casting of suitable metal, and of appropriate strength and rigidity. The central. portion of this support is recessed at 2 to form a supporting ledge for the range-finding mechanism, and a pair of flanges 3 and 4t are provided which serve for the attachment of a suitable housing which will protect the inechanisi'n and the support from atinos phcric and thermal influences. Arms 5 and (3 proceed in opposite directions from the central port-ion of the support or casting. these arms being preferably trough-shapml and taper as they proceed from the center. The end ofeach arm is formed with a base 7 and the primary reflectors S and 9 are firmly mounted in fixed position upon these bases. Any suitable means may be provided for rigidly supporting these primary re flectors in position. In the present instance, a vertical screw 10 is tapped into the respective base and its head engages a rigid arm 1.1. One end of this arm overhangs the top of the respective reflector and bears upon a cap 12, this cap in. turn pressing upon the top of the reflector and thereby causing it to rest firmly and immovably upon its base. The opposite end. of the arm 11 slidably en gages the top of a stationary rod 13 which rigidly secured to the base at a point removed from the reflector, and this end of the arm cooperates with a sleeve 14 which in turn is engaged by a spring 15. this spring bearing at its lower end against a shoulder 16 on the rod 13 and serving to compensate for temperature variations to the end that a sullicient pressure is main tained at all times upon the reflector to maintain it precisely in fixed relation to its base. A screw 17 may be tapped into the under side of the base and arranged to engage the lower side of the reflector at a point adjacent to its apex in order to facilitate the proper positioning of the reflector. An inner sleeve 18 preferably of tapered form is applied over each of the arms 5 and 6 of the cast-ing these inner sleeves being preferably secured rigidly to the central portion of the casting by screws or other means entering the flanges 3 and 4t, and an outer casing 19 also preferably of tapered form is supported by each of the inner sleeves and is rigidly secured to said sleeves. The central portion of the casting or support 1 is surrounded by a casing 29 which in order to render it removable is provided with slidable locking strips 29, spaces being formed between the sleeves and casings to substantially insulate the interior parts from the effects of heat. The outer casings 19 are provided toward their ends with glass-covered apertures 20 which are placed in front of the respective primary reflectors and admit light rays from an object to these primary reflectors. The central portion of the support or casting 1 is covered by a housing 21. and in order to facilitate the mounting or handling of the instrument a pair of oppositely arrangml handles 22 are secured to this housing 21. These handles are preferably connected by a cross-piece or blade and by placing this blade parallel, with the optical axis of the instrument, it may serve as a sighting device whereby the ope 'alor may direct the instrument approximately toward the object, the range of which is to be determined. The arms 5 and. (3 support lenses 2 1 and these lenses being interposed between the 1'0 spective primary reflectors and the secondary reflectors, which latter are adjustable in determining the different ranges. in the present instance, the secondary rellectors are superposed, that to say. one is arranged above theother, and in order to properly direct the light rays reflected from the two primary reflectors upon the respective sew ondary reflectors one of these lenses (the lens 25 in the present instance) is mounted for vertical adjustment and, in order to facilitate adjustment of this lens, suitable shafts 26 may be employed which are connected to each other and to the adjusting means for the lens by bevel gearing. and a milled wheel or head 27 within convenient reach of the operator serves to adjust the lens.

The rangclinding mechanism is contained within the central casing 29, the mechanism being mounted upon a support ing plate 28 which rests upon and firmly secured to the ledges 2 formed in the central portion. of the casting 1. The upper portion of this range-finding mechanisn'i is housed over by the substantially semi-circular housing 21 which is secured to the central portion of the casting 1 by the lugs 30 and screws 31. This covering or housing 21 may be removed, however, when desirable or necessary, the range-finding mechanism being then exposed for inspection or removal.

The range-finding mechanism embodies a telescope having an eye-piece a front section 33, and an outer housing or casing 34. This outer section 3 1 is stationary and is supported upon the plate 28 by means of a pair of brackets 35 and 36. The sections 82 and 33 of the eye-piece are adjustable tit axially with respect to the outer stationary section 3st and the section 33 is provided on one side with a rack 37, a guard 38 projecting outwardly beneath the rack. This rack forms part of the means for adjusting the section 33 forwardly and rearwardly for the purpose of focusing the telescope for long or short ranges. To enable the rack 37 to be operated conveniently from the exterior of the instrument casing, a pinion 39 is provided which coiiperates with the rack and is fixed to an adjusting shaft 40, this shaft being mounted in a bearing 41 which is attached to the plate 4-2 and this plate in turn is rigidly supported with respect to the plate 23, the shaft 40 having a milled head or adjusting wheel 43 which projects through openings in the member 29 and the central casing 21. I prefer to employ a pair of stops which may be suitably adjusted so that the telescope may be quickly focused, either for a. short range such, for instance, as would be used in standardizing the instrument by the aid of a target, and for a long range, such as would be used in deter mining the range or distance of an object. In the present instance, I provide a forward stop 44 which is attached to a cross-head 45 and a rearward stop .46 which is formed as a part of an adjustable bar 47, this bar 47 being attached to a second cross-head 48. The cross-head 4-5 is threaded to cooperate with an adjusting screw 4-9, the ends of which are journaled in suitable b arings 50 and 51. This screw L9 has a bevel gear 52 on its for ard end whicn cooperates with a bevel gear 53 attached to the lower end of an adjusting shaft 54-, this adjusting shaft being journaled in a sleeve 55 which is rigidly supported by a bracket 56 secured firmly to the base 28, and the upper end of this shaft 54 is provided with a milled head or operating wheel 57 which is arranged exteriorly of the central casing 21 and within convenient reach of the operator. The cross head which coiiperates with the screw 49 has a second aperture which, however, is slidable along a second screw 58, this second screw being also journaled at its ends in the bearings 50 and 51 and is threadedin the cross-head 48, this cross-head 43 being atta ched to the rear stop 46 and serving to adjust its position. The cross-head 48 has an aperture through which the screw 4-9 loosely passes and it is also fitted on its rear end with a bevel 59 which cooperates with a bevel gear 0 attached ti. an adjusting shaft 61, this adjusting shaf being journaled to revolve within a sleeve 62 which is fixed at its lower end by a bracket 63 to the supporting plate 28, and the upper end of the shaft 61 is provided with a milled head or operating wheel which is also exposed at the exterior of the instrument casing and enables the operator to conveniently adjust it. These forward and rear stops 44c and 5 .6 are in the path of the rack 37 attached to the focusing section 33 of the telescope and by suitably positioning these steps, they will cooperate with the respective ends of the rack and thereby automatically set the telescope for long and short range observations. The bar 4? which carries the rear stop 4-6 may be conveniently guided at its rear end by the rear supporting bracket 35 for the telescope, this bracket being provided with a recess (35 in which this bar 47 operates.

The secondary ref ectors which receive the images reflected thereon by the respective primary reflectors are mounted in front of the eyepiece and in axial alinement there with. The present invention provides improved means for mounting these secondary reflectors whereby they may be readily removed for cleaning and instantly eolaced precisely in proper position, and novel means provided for adjusting these secondary reflectors whereby the most accurate r ilts are obtainable in determining the different ranges. in the present instance, I provide a pair of. secondary reflectors 66 and (37, these reflectors being arranged in supm'posed relation and they are immovably secured to each other and to a detachable carriage 68. This carriage 68 I shall term a secondary carriage as it is mounted in turn upon a primary carriage The primary carriage 69 is of a novel construction, it avoiding the use of gibs or guides which are liable to introduce errors into the ultimate results of the instrument and. according to the present invention, no back-lash can possibly occur between either the primary or secondary carriages or between these carriages and the cooperative mechanism. 'i his primary carriage ($9 is mounted on and cooperates with a finely threaded screw "[0 which is revolved during'therangefindin operatioi'i so as to adiust the sec-- endarv reflectors axially w th respect to the eye-piece. This primary carriage so is provided at one side of the screw with a rib 71, one face 72 of which is vertical while its other face 73 is undercut.

The secondary carriage (i8 is provided with a groove, the upper wall 74: of which fits )(?l'l} upon the top flat face of the rib 71; it has a vertical wall which is f iarallel to the fiat vertical face 72 of the rib ii on the primary carriage. and the wall R3 of this groove is beveled to fit properly against the undercut face of the rib 71 on tie primary carriage. The vertical wall 75 f the groove in the sexindary carriage is spaced from the beveled wall 76 a distance gr ater than the spacing of the vertical and nude cut faces 72 and T3 of the rib in order that when the vertical wall of the groove in the secondary carriage is in'wed toward or brought into engagement with the ver t-ical wall 72 ot the rib, the beveled wall 70 will cl ar the undercut wall 73 of the rib and thereby permit the secondary carriage carrying the secondary reflectors to be headily detached.

To facilitate manipulation of the second ary carriage during removal and replacing, it is provided with a pair of stationary lingcr grips T7 and TH which are termed upon an arm which extends diagonally with respect to the rib-receiving groove in the sccoi'ldary carriage. This arm T0 ot the seccndary carriage is also provided with a thumb lever 80 which is slidably pivoted on t'h arm at S], one end ot this thumb lever having a grip at one end which is substantially opposed to the stationary grip Y7 and the other end of the thumb lever is connected to one end of a coiled tension spring H the other end ot' this spring being at tached to an eye 8s formed on the secondary carriage. t of the spring 83 which s ttachcd to the thumb lever 80 is formed a hook and this hook, vien the 2r grips T7 and S are relatively proxii. ited, can be engaged in a notch 86 formed in a lug 0? which proceeds diagonally from the L 'mary carriage no, and when the presure upon the thumb grip is re eased, the tension of the spring ti?) will cause the hook d3 thereon to seat itself in the notch 80 and That cm the spring 83 will then operate as a tenn inediun between the two ices i i carru which will draw the beveled wall Tb ot the groove in the secondary carriage tirmly against the undercut surface 73 of the rib Tl on the primary *arriage, the second: retlectcrs b'eing thereby positioned precisely with respect to the primary reflectors and the eye-piece. This spring 83 performs another tunction wluch \\'lli be herenianer described. The screw '70 which cooperates with and serves as a mounting tor the primary carriage ($0 is journaled at one end in a bearing 88 which is rigidly tixcd to the supporting plate the other end of the screw being journaled in a bearing St) which is also rigidly fixed to the plate That end ot' the screw which is journaled in the bearing is provided with a conical depression 90 in its axial center, and a tl'unst-sustaming member 01 is fitted into the bearing R9, in axial alinement with the screw and also has a conical. depression, 02 which is opposed to and is in alinement with the depression 00 in the screw. A piece of hard metal. 02} in the term of a double cone is interposed between. the screw T0 and the thrushsustaining member 91, the apices resting in the conical depressions 0t) and 02 respectively out these parts. This piece 93 sustains the thrust exerted upon the screw 70 with a 11111111111111 friction and, moreover, it will sustain the thrust properly, notwithstanding any lack of alinement that may develop between the screw and the thrust-sustaining member 01. The tln'ust-sustaining member 01 is preferably in the form of a plug fitted into the bearing 88. To retain this member in position, I prefer to employ an abutment 941 which substantially of angle form, one arm of the abutment pressing against the hiad of the member 01 which is preteralidy coned, as shown, and the other arm ol thc abutment is provided toward its rear edge with a rib 05) which rests upon the top of the supporting plate 38. it clan'iping screw passes through the abuti'ucnt in advance of the rib 95 thereon and is tapped into the supporting plate '28 and when this screw 0b is tightened, it will firmly clamp the thrustsustaining member 01 in proper position.

In order to maintain the primary and secondary carriages in proper position, to prevent these parts from turning or tilting about the screw 70 as an axis, and to elimi nate any back-lash that i'night have a tendency to develop between the prii'nary carri age and the screw and its thrust bearings, 1 provide the primary carriage 09 at opposite sides with knifcedgcs 07, and these knife-edges cooperate with a pair of hooks 08 formed upon a tension member 90. This tension member and the knife-edges are arranged diagonally with respect to the axis ot the range-finding screw 70, this tension member 90 projecting through an ()[Jtlllllg' in the supporting plate 28 and provided at it lower end with a point which rests in a cup 100 fixed to a thin flexible plate 102" and receives the pressure oil a spring 101, this spring, which is flexible in a single plane only, being supported by a bracket 102 which depends from the plate 28 and by the plate 102 which is fixed to the bracket 102, the spring being secured in position by a clamping screw 103. The angle through which the spring 101 exerts its force upon the primary carriage 69 corresponds approximately to the slope of the sides oil? the thrrads on the screw 70 and, owing to the angle hrough which the spring operates upon the primary carriage, this carriage wilbe constantly but yieldabl'y drawn in a direction that will retain it in such relation to the screw 70 as to prevent any back-lash and. moreover, the screw 70 will be held in proper engagement with the tlnrust-sustaining piece 93. The screw 70 is also held in proper engagement with the thrust-sustain ing piece 3 by means of a bow spring 10 lwhich ha a conical pin 105 attached to its intermediate portion which presses within a conical depression 1.06 formed in the for- 'ard end of the screw '10, and the two ends of this spring are sustained by lugs 10? formed on the plate 28.

During adjustment of the instrument to determine the ranges of different objects, the

carriage 69, together with the secondary refiectors, is shifted forwardly and rearwardly by revolving motion of the screw 70. Such motion is transmitted to the screw by means of a gear wheel 108 which in the present instance is secured to a hub 109 which is formed as a part of the screw, Motion is transmitted to the gear wheel 108 on the screw by means of a pinion 110 which is fixed to a shaft 111. This shaft 111 is journaled in bearings 112 and 113 which are rigidly fixed to the under side of the supporting plate 28, and this shaft 111 is also fitted with apair of bevel gears 114 and 115. The bevel gear 114 cooperates with a larger bevel gear 116 which is fixed to a vertical adjusting shaft 117. The upper end of this shaft 117 is reduced and is journaled in a bearing 118 attached to the supporting plate 28. The lower end of the shaft 117 has a handwheel 119 of suitable size fixed thereto, this hand-wheel serving as means by which the operator may adjust the instrument in de termining different ranges and also in standardizing the instrument by the aid of an in finity target. The shaft 117 immediately above the hand-wheel is steadied by means of a second bearing 120 which is also rigidly secured to the supporting plate 28. The shaft 117 is provided with an axial bore 121 and also with a diametrical slot 122. A plunger 123 is freely operable axially within the bore 121 of the shaft 117 and is pro vided toward its upper end with a cross-pin or bar 124 which operates freely in the diametrical slot 122 in the shaft 117 and is conneeted at its ends to a collar 125 which is freely shiftable axially from the exterior of the shaft 117 and is provided with a circumferential groove 126. Projections 127 ar ranged in diametrical relation upon a fork 128 engage in the groove 126, and this fork 128 is fixed to a rock shaft 129. The hub 130 of the hand-wheel 119 is hollow and contains a plunger 131, the upper end of which is fitted with a rounded head 132 adapted to press upon the lower end of the plunger 123 and thereby elevate the latter, and the lower end of the plunger 131 is provided with a collar 133 which is adapted to pass partially through an opening 134 formed in the axial center of the hand-wheel 119. The collar 133 is prevented from passing entirely through the opening 134 in the hand-wheel by a flange 135 which is formed upon its upper end. The plunger 131, however, may be held in elevated position by shifting it laterally after it has been elevated, the lower end of the collar 133 being provided for this purpose with an undercut groove 136 which is adapted to engage the beveled edge 137 of the opening 134. By returning the lower end of the plunger 131 to the axial center of the hand-wheel 119, it will be released and may then be lowered. The plunger 131 and the connected mechanism just described are parts of the means employed for opening the cover or shutter which exposes the scale of the instrument and simultaneously sets a brake upon the mechanism so as to prevent the adjustment from changing during or before a reading is taken and, by combining the operating plunger 131 with the handwheel 119 which serves to adjust the instrument for the different ranges, the operator is enabled to manipulate these parts with the greatest facility.

According to the present invention, a direct reading of the different ranges is obtained from a traveling tape, this tape being graduated and provided with figures indicating directly the different ranges and it is operatively connected to the hand-wheel 119 and to the screw which adjusts the secondary reflectors in determining the different ranges. The tape mechanism is not claimed in this application, but it will be described generally in order that a clear understanding may be had of the complete instrument. The tape or band 138 which is graduated or contains numerals corresponding to the different ranges is of a suitable length and its ends are attached to upper and lower reels 139 and 140. The shafts 141 and 142 respectively which revolve with these reels are provided with pinions 143 and 144. The pinion 143 cotiperates with a gear wheel 145 while the pinion 144 cooperates with a gear wheel 146. These gear wheels 145 and 146 are mounted upon a common shaft 147, and a spiral spring 148 is interposed between the wheels, one end of the spring being attached to the wheel 145 while the other end of the spring is attached to the wheel 146. The action of the spring 148 is to maintain the tape taut, both reels having a tendency to wind the band or tape. While the tape is being unwound from one reel and wound upon the other, it is obvious, however, that the speed of rotation of the two reels will vary, but owing to the differential action of the gear wheels 145 and 146, together with the compensating spring 148, this variation in rate of movement of the reels will be provided for and the band or tape will be kept taut at all times. A sprocket wheel 149 is interposed between the reels and cooperates with the tape to impart movement thereto from the range-finding mechanism. In order to pro vide a proper driving connection between the band or tape and this sprocket wheel, the latter is provided with teeth 150 adja cent to its opposite edges which co'tiperate with the rows of regularly spaced apertures 151 formed adjacent to the two marginal edges of the tape. The sprocket wheel 149 is mounted upon a shaft 152 and this shaft I is fitted with a driving gear 153. This driving gear 153 cooperates with a gear 154 and this gear is fixed to a shaft 155 ournaled 111 bearings 156 and 157 secured to the under side of the supporting plate 28. The opposite end of the shaft 155 is provided with a bevel pinion 158 which cooperates with the relatively large bevel gear 115 on the shaft 11.1. As the sprocket wheel which drives the tape and the screw which adjusts the secondary reflectors are both operatively connected in predetermined relation to the hand-wheel 11.9, it is obvious that the tape will be shifted in a predetermined ratio to the movement incident to the adjustment of the secondary reflectors. The gear 15 1 is preferably provided with a brake flange 159 whereby the tape may be held from movement while a reading is being taken from the tape. According to the present invention, 1 also provide means for automatically producing a braking effect upon the tape when the movementof the tape in one direction approaches the infinity mark and while the movement of the tape in the opposite direction approaches its end, the attention of the operator being thereby automatically directed to the fact that the instrument has approximately reached an adjustment where it may be standardized by the aid of an infinity target, and it also directs the attention of the operator to the fact that the traveling band or tape is approaching its end so that stripping of the band from either spool. is prevented. To this end, the shaft 111 is formed as a screw 160 of suitable pitch, and this screw cooperates with a traveling crosshead 161 which is suitably guided by the under side of the supporting plate 28. This cross-head has a fork 162 which straddles a rod 163, this red being preferably formed as a screw and one end thereof is slidably engaged in a lug 164: fixed to the supporting plate 28. Stops 165 and 166 are secured at appropriate points toward the opposite ends of the threaded rod 163, these stops in the present instance being in the form of two nuts locked together whereby they may be adjusted so as to be engaged by the fork 162 on the cross-head as the tape approaches the limit of its movement in either direction, and continued rotation of the screw 160 will cause the rod 163 to be shifted to automatically set the brake upon the brake flange 159 on the gear 15-1. The brake in the present instance consists of a pair of brake shoes .167 and 168 which are formed on a sleeve 169, and this sleeve is journaled on a pin 170 which in order to enable the parts to be readily taken apart and assembled is removable, one end of the pin being engaged in an apertured lug 171 formed on the supporting plate 28 while the opposite end of this pin is rotatably fitted in a bearing lug 172 which forms an abutment for the brakeoperating sleeve 169. The end of the pin ad acent to the bearing lug 172 may be formed with an eye 173 which serves as a handle to facilitate removal and insertion of the pin. The brake-operating sleeve 169 has a crank 17 4!: fixed thereto, and this crank is opcratively connected to an offset arm 175 formed as a part of the rod 163.

In order to normally hold both brake shoes 167 and 168 out of engagement with the brake flange 159 on the gear 15 1 and thus permit the traveling band or tape to shift withoutresistance, a rocker 176 fixed to the brake-operating sleeve 169 and it has a flat under side which cooperates with a flat spring 177 which spring may be conveniently inserted in a recess 178 formed in the supporting plate 28. This spring normally acts upon the flat face of the rocker 176 to hold the two brake shoes 167 and 168 in neutral position, but rotation of the sleeve 169, owing to movement of the rod 163 in either direction, will cause one of the brake shoes to act upon the brake flange 159 of the gear 154-, thereby resist- .ing further rotation of the tape and this resistance to the further movement of the tape or band will be felt by the operator while 111211111Jl1l2t11l11g the hand-wheel 119.

Reading of the munerals upon the travel-- ing band or tape is controlled by a shutter 179 which is so mounted as to move to and from a position in front of that portion of the band or tape engaged by the sprocket wheel, the observation of the tape being made through a suitable glass-covered sight aperture 180 formed in the inclosing casing of the instrument and to render the numerals or mar {S on the band readily readable, 1 preferably provide an electric illuminating lamp 181 which is mounted so as to direct its rays upon the band. This shutter 179 in the present instance has arms 182 which are pivoted on fixed axes 183, and one of the arms is connected by a rod 181- to a lever 185 which lever is fixed to the rock shaft 129 whereby upward movement. of the plunger-s 123 anddkll will pull upon the rod 181 and thereby lift and open the shutter to enable a reading to be had of the traveling band or tape and, when these plungers are permitted to descend, the shutter will immediately close and cover the traveling band or tape. Gravity may serve to produce closing movement of the shutter but in the present instance, 1 have shown a spring 186 which surrounds the shaft 12%) and also acts to produce closing movement of the shutter. Means is also provided for automatically producing a braking action upon the traveling band or tape whenever the shutter is opened or lifted in order that a change in the adjustment of the instrument cannot occur before or during a reading of the band or tape. In the present instance, the lever 185 is provided with an arm 187 which has one end offset to form a brake shoe 188, this brake shoe on the arm 187 being arranged within the brake flange 159 on the gear 154, and it will be seen that when the shutter is opened, this same movement of the parts will cause the brake shoe 188 to be set, this bra ring action, however, being immediately released when the shutter closes. The present invention also provides means whereby the instrument may he readily and accurately standardized by the aid of an infinity target. According to the present invention, this infinity adjustment is so related to the range-finding adjustment that when the instrument is in condition for deermining ranges, the infinity adjustment is automatically locked so that it cannot be disturbed and when the ii'strument in condition for standardization by the aid of an infinity target, the mechanism for determining ranges is automatically locked so that its adjustment cannot be altered. lvleans is also provided by the present invention for producing a suitable amount of slack or backlash between the infinity-adjusting means and the carriages which support the secondary reflectors.

In the present instance the standardization of the instrument is effected by properly adjusting the secondary carriage (38 which carries the secondary reflectors, with respect to the primary carriage 69 which is operatively associated with the range-finding mechanism. In the present instance, the primary carriage 69 has a threaded lug 189 into which an infinity adjustment screw 191 is fitted. One end of this screw abuts against the adjacent edge of the secondary carriage 68 carrying the secondary reflectors. This infinity adjustment screw is provided with suitable means for preventing its accidental turning. In the present instance, it is held at the different adjustment-s by friction produced upon the screw by the lug 189 and the toothed wheel 192 which is threaded'upon the screw and abuts against the lug 189 after the manner of a lock nut.

A suitable stop 193 cooperates with thetoothed periphery of the wheel 192 and serves to retain it in the different adjusted positions. This infinity adjustment screw 191 moves with the carriage 69 during the adjustment of the instrument in determin ing the different ranges, and the detachable secondary carriage GS is held at alltimes in engagement with the end of the infinity adjustment screw under the tension of the spring 83, this spring acting diagonally with respect to theaxis of the infinity adjustment screw.

The end of the screw 191 opposite to that engaged by the secondary carriage 68 is provided with a square or other angularshaped portion 191- which forms part of a coupling through which this infinity adjust ment screw is eperatively connected with infinity adjustment mechanism which is mounted in stationary relation upon the supporting plate 28. This mechanism in the present instance embodies a bearing 195 .Wnicll is fixed immovably upon the upper side of the supporting plate 28 and has a shaft 196 journaled therein, one end of this shaft carrying a bevel gear 197 by which the shaft is rotated, and the opposite end of this shaft 190 has a squared or other angularshaped portion. 198 which is coinpleniental to the square or angular-shaped portion 19% formed on the infinity adjustment screw. Obviously, during adjustment of the instrument in determining different ranges, the infinity adjustment screw will move toward or from the shaft 190, it being in axial alint ment with this shaft. 1'. provide means, how ever, for maintaining operative connection between the infinity adjustment screw and this shaft 190, irrespective of the relative D'lUVtlHQDtS between the parts, such n'ieans consisting in the present instance of coupling 199, the ends of which fit loosely upon the angular portions 19 1 and so as to transmit rotation between the shaft 196 and the infinity adjustment screw, but the coupling has a sliding engagement with these angular portions on the infini y adjustment screw and the shaft which compensates for the relative approaching and receding movement between these parts.

The present invention provides means for maintaining a proper amount of slack or looseness between the coupling and the in finity adjustment screw and shaft in order to eliminate friction at this point during the adjustment of the instrument. in determining the different ranges. The upper portion of "he bearing 195 is formed with a stationary sleeve 200 which in the present instance is arranged vertically. A. hollow shaft 201 is rotatably fittec within the sleeve 200 and is formed at its lower end with a bevel. pinion 202 which cooperates with the bevel gear 197. In order to detachably hold the hollow shaft 201 in position, its upper end is formed with a circumferential groove 203, and a. spring latch 20 1 is fixed to the exterior of the sleeve 200 and has a dog 205 which engages in the groove 203 and thereby pres vents upward movement of the hollow shaft 201, although it will germit this hollow shaft to rotate. The hollow shaft 201 is operated by an inner stem 206, a portion of which is square or angular in cross-section and fits a correspondingly-shaped bore in the upper portion of this shaft 201 so that while the stem 206 may move axially with respect to the shaft 201, a driving conneo tion is maintained between the parts. The lower end of the stem 206 extends loosely through the bottom of the hollow shaft 201 and engages in a socket 207, this socket having a journal portion 208 which fits into an elevating link 209, and in order to detachice ably connect the stem 206 to its socket 207, the lower end of the stem 206 is provided with a cireun'rt'erential. groove 210 while the journal portion 208 has a bore which receives an arm 911 of a locking clip. This locking clip has a resilient looped portion 212, the end of which is beveled to form a locking dog 213 to engage in a notch Ql-il formed in the journal portion 208 and when the dog 21 engaged in this notch, the end ot the arm 2t]. will rest in the circumlieren tial groove 21.0 in the stem 20c and thereby detachably lock the latter in position. In order to remove the stem 206, it is only necessary to bend the loop so as to disengage the dog 213 thereon from the notch 21% whereupon the arm 211 of this clip may be withdrawn from engagement; with the groove 210 in the stem. The link 209 forms part oil mechanism which places the operating means for the infinity adjustment in condition to be operated when the traveling tape or band is in proper position for standardizing of the instrlnnent. This mechanism consists in the present instance of a rock shaft 215 having a crank 216 thereon which is pivotally connected to the upper end of the link 209 so as to lift the latter tog ther with the stem 206 wnen rotated in one (illlOCl'lOIl and to permit such parts to be lowered when rotated. in a reverse direction. This shaft 215 in the present instance is in. the term of a sleeve and it is journaled upon a pivot pin 217, the ends of which are supported in the lu'ackets 35 and 3G for the telescope eyepiece and a spring 218 surrounds the tubular shaft and normally acts to return the stem 206 in lowered position and to yieldably hold. this stem in such position. T his tulmlar sl'iatt 215 is operated by a crank 219 which is tixed thereon. and is pivotally connected to a link 220, this link having a pin 221 which operatively connects it to a bevel gear 222. This bevel gear is fixed to a shaitt 223. the latter being suitably jonrnaled in a bearing bracket 22%.

In order that the link 320 may clear the shatt 223 and the hub ot the bevel gear when the tubular shaft 215 is rocked in a direction to the i1'iiinity-adjusting means in condition to be opera ted, it is bent in the manner shown in Figs. 20 and 2]. ll hen the infinity adjustment mechanism is in this condition, the pivot pin 221 which attaches the link 220 to the bevel 222 is pret' eribly slightly beyond the axis oi the shaft 223} in order that the spring 218 may then be inactive to return the inlinity adjust; ment mechanism to inoperative condition. Any suitable means may be provided for operating the bevel gear 222 from the exte rior ot' the instrument casing. In the present instance, I provide a bevel gear 226 which cooperates with the bevel gear 222 and. is fixed to an operating shait't 2-27, the

latter being mounted revolubly in a sleeve 228 which is fixed to the bearing bracket 2% and. the upper end of the shalt 227 is operatively connected to a handle 229 which is exposed at the exterior of the instrument casing as shown in 7. in order to enablethis handle to be readily removed and replaced during dismantling of the instrmuent, it has a tubular stem 230, the lower end of which is -formed with a diametrical rib 231 which detachably engages and forms a coupling with the upper slotted end 232 of the shaft 227. l he tubular stem 230 has a telescopic fit into the upper end of the sleeve 228 a ad. in order to (.letachably lock the handle 22D and tubular stem 230 in position the upper end of the sleeve is provided. with. a circumferential groove 233 while the tubular stem 230 contains a plunger 23st; which is shittable axially within the stem, its upper end projecting slightly above the top of the handle 229 to term a press-button, and a spring 2 35 serves to normally hold the plunger in elevated position with the press-ln'ltton projecting above the handle 229. A. latch 236 is pivoted within the plunger 23st at 237 and has a dog n38 which extends diagonally to the axis of the plunger and projects through a diagonal opening formed in the wall of the tubular stem 230, and a spring 2 39 behind the latch serves to yieldingly press it into locking position. Vv'hen the handle is applied, the diagonally inclined dog will project through the tubular stein 230 and will engage in the circumferential groove 23 formed in the top of the sleeve 228, thereby maintaining the handle and its stem in operative relation with the shat't 227. lVhen, however, it is desirable to detach the handle and its stem, it is only necessary to depress the plunger 2341:, the diagonal dog 2238 on the latch being thereby carried into engagement with the slot in the wall of the tubular stem 230 against the action of the spring and the latch is thereby drawn within the stem so as to disengage from the circumtierential groove 233 in the sleeve it being then possible to withdraw the stem 230 from the upper end of the sleeve in order to lock the graduated tape or band from movement while the instrument is being standardized by the aid of an intinity target or object, the gear wheel 15? which serves to operate the traveling tape or band, owing to its connection with the sprocket wheel 149, is provided with an aperture Ell), a gear wheel 1.53 mounted adjacent to the gear wheel 1433 and cooperates with a pinion turnable therewith, this wheel 153 has an aperture 24:0, and a reciprocatory locking bar is adapted to enter these apertures 240 and 240 only when they register and thereby lock the tape from movement only when the infinity mark on the tape is in proper position for infinity adjustment of the instrument and preparatory to such adjustment. This reciprocatory locking bar 2&1 operates loosely through a supporting bracket 2&2 at a point adjacent to the gear wheel 153 and its oppo site end operates through an aperture formed in an arm 2&3 which proceeds upwardly from and forms part of the rear bracket 35 for the telescope eye-piece. A link 2&& is pivotally connected to this locking bar 2&1 and it is also attached pivotally to a crank 2&5 which is fixed to the tubular shaft 215 so that when this shaft 215 is rotated by operation of the handle 229 to set the instrument in condition for the infinity adjustment, this locking bar 2&1 will enter the aperture 2&0 in the gear wheel 153 and will thereby lock the tape in proper position.

lVhile the instrument is in condition for adjustment in determining the different ranges, the handle 229 and its connected parts are locked from operation. This result is accomplished in the present instance by an arm 2&6 which is fixed to the shaft 223 carrying the bevel gear 222 and this arm while the instrument is in condition for range-finding is locked behind a dog 2&7 fixed to the brake-operating shaft 169. Ohviously, while the instrument is in condition for range-finding, this brake-operating shaft 169 will be in a neutral position with the brake shoes 167 and 168 in inoperative condition. When, however, the instrument is so adjusted as to bring the infinity mark upon the tape into a position to register with the sight opening, the brake 167 will operate to arrest further movement of the tape by reason of the rocking of the shaft 169 in the direction indicated by the arrow in Fig. 21. VJ ien the shaft 169 is rocked in this manner, the dog 2&7 is carried out of the locking position as shown in Fig. 20 and into the releasing position shown in Fig. 21, the arm 2&6 being then free to rotate into the position shown in Fig. 21 while the bar 2&1 is moving into locking position. and the stem 206 is being elevated as indicated by the arrows in Fig. 21.

According to the present invention, the infinitely-adjusting means is incapable of operation while the instrument is in condition for range-finding. In the present instance this result is accomplished by providing an operating part in the form of a milled head or wheel 2 8 which is carried by a stem 2&9 operatively connected to and shiftable vertically with the stem 206, this wheel being nested within a housing in the form of a flange 2&9 on the top of the casing while the instrument is in condition for rangefinding and when in condition for the infinity adjustment, this milled wheel is elevated above or moved out of its housing and is then accessible for manipulation owing to the lifting of the stem 206. In the present instance this stem 2&9 is detachably fitted into a socket 250 formed upon the upper end of the stem 206, the bottom of this socket having a slot 251 which receives and forms a driving connection with a transverse rib 252 upon the lower end of the stem 2&9, and the upper end of the socket 250 is provided with a hub 253 having an interior circumterential groove 25&. The stem 2&9 contains an axially movable plunger 25& the lower end of which is acted upon by a compression spring 255 which serves to yieldingly hold the press-button 256 formed upon the upper end of this plunger above the milled wheel 2&9. A latch 257 is pivotally attached to the plunger at 253 and it has a dog 259 which extends diagonally with respect to the direction of movement of the plunger and projects through an opening 260 formed in the wall of the tubular stem 2&9 so as to engage in the internal circumferential groove 25& in the hub portion 253 of the socket 250. The latch is yieldingly held in such position by a spring 261 and when the dog is in looking position, the milled wheel 2&8 and the dog and its connected parts are held from detachment or displacement. To detach the milled wheel, however, it is only necessary to depress the button 256, the diagonally extending dog 259 being thereby retracted and withdrawn from the groove 25&.

Means is provided for maintaining suflicient slack to prevent binding between the coupling 199 and the cooperative portions of the infinity adjustment screw 191 and the shaft 196. Such means consists in the present instance of a housing 262 which is formed as a part of the sleeve 200, the hub 253 attached to the socket 250 being provided with a pair of depending fingers 263 which enter the housing. This housing is hollow to contain suitable compensating iechanism which consists in the present instance of a pair of superpo. ed disks 26& and 265 which are journaled to rotate about a hub portion 266 within the housing, and the disk 26& is provided with a pair of diametrically spaced lugs 267 while the disk 265 is provided with a pair of diametrically spaced lugs 263. These disks are so placed within the housing as to leave a space be tween the lugs 267 and 263 thereon, and the depending fingers 263 attached to the hub 253 rest in the spaces between these lugs. A set of springs 269 are interposed between the lugs 267 and 268 which are shittable with respect to the housing 262 and a pair of lugs 270,'these lugs 270 being formed as inward extensions of a flange 271 attached to a plate 272, this plate forming a cover for the housing 262 and its contained parts and having slots 273 of suitable length in which the flanges may operate freely through a limited angle. This plate 272 is rotatable about the hub portion 266 and is detachably held in position by a retaining ring 27st which issprung into an exterior circumt'erential groove 275 formed in a hub-like extension or the housing 262. A pair of pins 276 extend downwardly into the hous ing from the plate 272 and rest between the opposed lugs 26? and 268 of the disks 2M and 265. These pins also extend loosely through slots 277 formed at diametrically opposite points in the flange 278 of a ring 279, this ring being centered upon and rotatable about an annular shoulder 280 formed within the housing and serves as at retainer tor the springs 269. During rotation of the fingers 263 to adjust the instrm'nent tor infinity range, the ends of these fingers will cooperate with the ends of the slots 278 in the plate 272, and the plate 272 together with the mechanism within the housing will rotate during the infinity adjustment. \Vhen such adjustmenthas been eompletech however, the springs 269 will operate auton'iatically to return the fingers 263 to substantially the centers of the slots 273, this involving a slight retrograde movement of the hollow shaft 201 which is operatively connected through the bevel pinion 202 and the bevel gear 19'? to the shaft 196. This retrograde movement will be just sulficient to loosen any binding action that might be present between the angular portions 1% and 198 on the infinity adjustment screw 191 and the shaft 196 so that during the adjustment of the instrument for range-finding, no resistance to such adjustment will be otlered by the coupling 199.

In standardizing the instrument by the aid of an infinity target, I have found in practice that it is necessary to separate the images from the two secondary reflectors (3G and 67 in order that images of suitable definition will be obtained and that an accurate adjustment of the instrument may be secured by precisely superposing the images. I have provided a device for accomplishing this result which accordii'ig to the present embodiment of the invention is auto matically brought into position when the eye-piece of the telescope is adjusted for the infinity target, and when the eye-piece of the telescope is adjusted for range-finding, this image-separating device will 1e automatically moved aside. lhis device consists in the present instance of a plate or septum 281 which is secured to an appropriate carrier 282, this carrier having a pair of arms 283 which are pivoted at 284: to a lug! 285 which may be formed upon the top of the eye-piece supporting bracket 36. This carrier is provided with a suitable spring 286 which normally acts to move itinto operative position before the eye-piece. The

carrier is also provided with a pair or curved fingers 287 which are engaged by 30 the forward end of the slidable section ho of the eyepiece so that when this section of the eyepiece is extended forwardly or shift ed toward the secondary rellectors it will act upon the curved fingers 287 and will thereby lift the carrier into the position shown in Fig. 8 and when the section 3 ot the eye-piece is moved rearwardly or in the direction away from the secondary retlectors, the carrier is permitted to move into a position between the eye-piece and the secondary reflectors. lVhen the plate or septum 281 is in proper positiom it occupies a plane in alinoment with the plane upon which the secondary reflectors on and (57 are united, and in order to insure a proper positioning of the plate or septum 281 in this respect a set-screw 288 may be tapped into the carrier and arranged to bear upon the top of the stationary or outer section 34 ot' the telescope eye-piece, This septum 281 enables two sharply separated and defined images to he obtained from the secondary retlcctors (36 and (ST, and it has been found that a precise and quick adjustment of the instrument obtainaliile.

The rear section of the telescope eyepiece extends through suitable openings in the casing of the instrument and is in a convenient position to receive the eye of the operator. This section of the eye piece is arranged toward one side of a light-excluding hood 289 which is attached to the (X- tcrior of the instrument. lln some instances it may be desirable or preilierable to employ a finder to serve as means for locating an object in order that the instrument may be aimed, at the same. In the present instance ll provide a finder which embodies a lower reflector and an upper reflector 2M both mounted in fixed relation upon a standard 292 fixed in a suitable manner upon the supporting plate 28, a third reflector 293 which is also fixed upon the up per portion. of the standard 292, and another reflector 294t which is attached to the upper end of the vertical. arm The relector 294 is in line to receive the rays en tering the instrument through the glasscovered aperture which is arranged at the front of the instrument while this reflector 29 11 bends the rays laterally out of alinement with the aperture 295 and the retlectors 2S) and. 291 bring the rays into a. position to be received by the right eye ot the operator while the left eye may be placed in alincment with the eye-piece oi" the rangofinding telescope. The observation by i'neans of the finder is had through an aperture 296 which is formed at the right hand side of the hood 289 and this aperture may be closed by a slide 29? which carries suitable plain transparent glass. in

order that the distance between the range finding telescope eye-piece and the finder may agree with the pupillary distance of the eyes of the operator, the standard 292 which supports the reflectors 290, 291 and 293 is mounted to shift in guides 298 formed upon the top of the supporting plate 28, the lower end of the standard being formed as a base which serves as a slide and it has a rack 299 attached thereto which cooperates with a pinion 300. This pinion 300 is fixed to a shaft 301 journaled in bearings 302 formed upon the top of the supporting plate 28, and such shaft projects to the exterior of the instrument casing and is provided with a milled wheel 303 or other suitable means for manipulating it.

The instrument may be 'mounted in any suitable cradle or stand which will afford the necessary adjustments for the entire instrument about a vertical of a horizontal axis. The under side of the instrument casing is preferably provided with a plate 304 of suitable strength, and a pair of longitudinally spaced lugs 305 project down wardly from this plate and a second pair of circumferentially spaced lugs 306 also project downwardly from the plate, these four lugs serving as legs to support the instrument when demounted, and the lugs 306 also preferably serve as means for securing the instrument from displacement with respect to the cradle or stand which supports it. To facilitate mounting and dismantling of the instrument, the milled heads or operating wheels d3, 57 and 64, as well as the milled head or operating wheels 243 and 303 and the handle 229, are preferably detachable and are provided with suitable means for removably locking them in position.

A range-finding instrument constructed in accordance with the present embodiment of my invention may be operated as follows Preparatory to using the instrument for the purpose of determining the ranges of dis tant objects, it is preferable, if not essential to accurate results, that the instrument be standardized with respect to an infinity range. I prefer to use an infinity target as an aid to the operation of standardizing the instrument which supports objects which are separated a distance equal to the optical distance between the two primary reflectors of the instrument, although a star may be utilized as an object at an infinite range. To prepare the instrument for standardization at the infinity range, the hand-wheel 119 is revolved by the operator in the proper direction until the graduated tape or band is brought into a position where an infinity mark located thereon at the proper point registers with the glass-covered sight opening 180. As this infinity mark on the tape is approached, the screw 160 will carry the cross-head 161 into a position to engage and shift the top 166 on the threaded rod 163, this rod 163 being thereby shifted and it will then act upon the brake-operating shaft 169 to rock it from the neutral position shown in Fig. 20 into the position shown in Fig. 21, the brake shoe 167 being thereby caused to act upon the brake band or flange of the wheel 15 1- and further movement of the graduated tape will be resisted and such resistance will be felt by the operator in turning the handwheel 119. This automatic setting of the brake is a signal to the operator that the tape is approaching that end thereof which contains the infinity mark. When the infinity mark on the tape is in pro-per position, the handle 229 may be turned into the position shown in Fig. 21, the arm 246 at this time being free of the dog 2 17 and the locking bar 2 11 may enter the locking apertures in the gear wheels 153 and 1 53. When the instrument is in this condition, the rangefinding mechanism which includes the traveling tape and the range-finding screw 70, both of which are operatively connected to the hand-wheel 119, will be locked from operation. As the handle 229 is turned into the position shown in Fig. 21, the stem 206 will be elevated, causing a corresponding elevation of the stem 2 1 9 and the milled head or operating wheel 2 18 as indicated by the arrows in Fig. 21. Before the instrument is in condition for the infinity adjustment, this milled wheel 248 is nested within the housing or flange so that it would be impossible to disturb or alter the adjustment of the instrument by the infinity ad just-ment mechanism while the instrun ent is in condition for range-finding. When this operating wheel is exposed or elevated above its housing, however, it is then free to be rotated. Rotation of this wheel 2&8 operates through the connections hereinbefore de scribed to turn the shaft 196, and such movement is transmitted through the compensating coupling 199 to the infinity adjustment screw 191. As the secondary carriage (36 to which the secondary reflectors are attached is maintained in engagement with the end of this infinity adjustment screw by the spring 83, turning of the infinity adjustment screw 191 will cause relative shift ing movement between the secondary carriage 68 and the primary carriage In standardizing the instrument with the aid of an infinity target, the sections 32 and 33 of the eye-piece are shifted toward the left in Fig. 8 and this will allow the septum or dividing plate 281 to move into a position that will enable the operator to observe two clearly separated and defined images, one from each of the superposed secondary reflectors. After the instrument has been standardized, a slight retrograde movebinding or friction of these parts with th ons 32 and 33 o and 64; may

forwardly and r l 0 tively connected to the traveling tape.

ment will be imparted to the shaft 196 which will produce sullicient looseness or slack between this shaft, the infinity adjustment screw and the coupling 193) as to i void any coupling that would otherwise resist h movement of the primary and secondary car riages during thi adjustment of the instrnment in determining the adherent angers.

re The mechanism for producing this slack or looseness for such purpose has been hereinbetore described in detail.

After the instrument has been standardized with the aid of an inlinity target, 'l t he teles -opeeyepiec are then shifted to the right in .liig. 8 which will properly "focus the instrument for 'ange-finding distances, the carrier 282 supporting the septum 5281 being thereby auto- 20 matically moved into an inoperative posi- T his will. .immeoiatcly return the 35,1nilled head 24:8 into an inaccessible position within its housing 249 so that the in finity adjustment cannot be disturbed and at the same time the locking bar Qlil will be disengaged from the w eel lo?) operry turning the hand-wheel 1119, range-finding screw 70 will be rerolred, thereby shiit ing the ondary reflectors while the images are observed by the zu erator through on up the telescope eye-piece.

Vfhen the instrument has been adjusted to conform to the range of tie object, it will be found that a. direct reading of the range or distance may he o e-tamer from the trai eling tape by an lDSJ tlOD ot the numerals ugh the sight apirevi usly' described, l to the range bein o )erativel t) P-' I 1e 1s sinrted finding screw 5 1 from the inlini d 163 will be permitt d to "m l position, the brake-r p aeing then returned to n by the spring 177 anti ting effect 59 upon the tapt d itment of the instrument Q i the Should the ha d 1 j is reyolyeo sutficiently to ca he or end. of tl'ie taoe to approach the sight opening, then the traveling cross-head or carriage 161 would engage the stop 1G5 and shitt it so as to reel; the shaft 169 into a position to bring the brake shoe 168 into action, the resistancc thus oit'ered to the further movement of the tape notifying the operator that the tape is approaching its end and thereby preventing the tape from being stripped from its spool or reel.

1 claim as my invention 1. In a range tinder, the coin iination o'li range-finding mechanism, a traveling indicaring tape graduated according to the difterent ranges and operatively associated with the range-finding mechanism, and a brake operatire automatically to resist movement of the tape when it approaches a predetermined point in its movement.

2. in a range tinder, the combination of range-finding mechanisi'n, a traveling indicating tape graduated according to the dil? terent ranges and operatively connected to the ange-linding mechanism, and a. brake ope 'atire automatically by the range-linding mechanism for arresting the movement of the tape when it approaches a predetermined point in its morement.

in a 'ango tinder, the co "bination oi? range-finding mechanism, a traveling ind cating tape graduated according to the different ranges and operatirely connected to more according to the dilierent adjustments of the range'tinding mechanism, spools to wl'iich the ends ot said tape are attached, and a brake operative automatically to resist further movement of the tape before it has been completely unwound LtlOlll one of said spools.

l. in a range finder, the combination of 'ange-finding mechanism, a traveling indiating tape graduated according to the ditierent ranges and opera 'iyely connected to the range-finding mechanism, a pair 0t spools to which the ends of said tape are attached, and a double-acting brake operative automatically to arrest further movement of the tape prior to the complete unwinding of the tape from either spool.

In a range tinder, the combination oii ange-linding mechanism, a traveling indi- *ating tape gradrnited according to the ditterent ranges and also provided toward one end with an infinity adjustment mark, said tape being operatirely connected to the range-finding meclnrnism, and a bralte operative automatically to res the movement oi? the tape when the hilarity adjustment mark thereon reaches an ogeratrve position.

6. in a range tinder, the combination of range-finding mechanism. inch'rding a screw, a traveling tape graduated according to the diitterent ranges and operatirely connected to the 'ange-iinding i echanism, a doubleacting b *ahe operr tiyely associated with the t -aveling tape, an actuating rod connected to the brake and having a pair of stops,

and a cross-head actuated by said screw and cooperative automatically with either of said stops to resist further movement of said tape when it reaches predetermined limits in its movement in either direction.

7. In a range finder, the combination of a range-finding screw, a carriage adjustable thereby, indicating means operati\ ely connected to the range-finding screw, a secondary carriage-movable relatively to the carriage first mentioned and carrying optical parts of the range-finding mechanism, and an infinity adjustment screw fitted to one of the carriages and cooperative with the other carriage for efiecting and maintaining different relative adjustments between the carriages.

8. In a range finder, the combination of a range-finding screw and indicating means operatively connected thereto, a primary carriage cooperative with said screw, a secondary carriage mounted on and shiftable axially with respect to the primary carriage and having optical parts of the range-finding mechanism attached thereto, an infinity adjustment screw fitted to one of the carriages and cooperative with the other carriage for effecting and maintaining different relative adjustments between them, and operating means for the infinity adjustment screw having a device for maintaining 0perative connection with the infinity adjustment screw irrespective of the shifting movements of the carriages in determining different ranges.

9. In a range finder, the combination of a range-finding screw, a primary carriage cooperative therewith, a secondary carriage mounted on and shittable axially with respect to the primary carriage, primary and secondary reflectors, the secondary reflectors being attached to the secondary carriage, an infinity adjustment screw fitted to one of the carriages and cooperative with the other carriage for effecting and maintaining different relative adjustments between the carriages, operating means for the infinity adjustment screw, a coupling between. the operating means and the infinity adjustment screw for maintaining a connection between the parts irrespective of relative shifting movements between them in determining diflerent ranges, and means for producing slack between said coupling and the infinity adjustment screw after each adjustment of the latter.

10. In a range finder, the combination of a range-finding screw, a primary carriage cooperative therewith, primary and secondary reflectors, a secondary carriage mounted on and shiftable axially with respect to the primary carriage and having the secondary reflectors fixed thereon, an infinity adjust ment screw carried by one of the carriages and cooperative with the other carriage for tachably mounted on the primary carriage and having the secondary reflectors fixed thereto.

12. In a range finder, range-finding mechanism including a range-finding screw, aprimary carriage cooperative therewith, a secondary carriage detachably mounted on the primary carriage and having secondary reflectors fixed thereto, and means for retaining the secondary carriage in proper op erative relation with the primary carriage.

13. In a range finder, range-finding mechanism including a range-finding screw, a primary carriage cooperative therewith, a

secondary carriage having a detachable connection with the primary carriage and also having reflectors fixed thereto, and a spring adapted to act upon the carriages to retain them in proper operative relation.

14. In a range finder, range-finding mechanism including a range-finding screw, a primary carriage cooperative therewith, a secondary carriage having means for detachably mounting it upon the primary carriage and supporting reflectors in fixed rela tion thereon, a spring attached at one end to the secondary carriage and having a hook at its opposite end, and a lever slidably pivoted on the secondary carriage and connected to the hooked end of the spring whereby the hook portion of the spring may be engaged and disengaged with respect to the primary carriage.

15. In a range finder, range-finding mechanism including a range-finding screw, a primary carriage cooperative therewith, a secondary carriage having reflectors mounted in fixed relation thereon, a rib on one of the carriages extending axially with respect to the range-finding screw and forming a detachable connection with the other carriage, an infinity adjustment screw fitted to one of the carriages and cooperative with the other carriage, and a spring acting in a diagonal direction wit-h respect to the axes of said screws and serving to retain the carriages in connected relation to one another and with respect to the infinity adj ustment screw. 

